1. Field of the Invention
The present invention relates to an obstacle detection apparatus.
2. Description of the Related Art
The development of the technology for ensuring safety for a motor vehicle driver by mounting various sensors in and on the vehicle and monitoring its periphery is in active progress. Such technology includes, for example, the adaptive cruise control (ACC) intended to maintain a safe distance between an own vehicle and the immediately preceding vehicle by using a radar installed at the front position of the host vehicle. The development of a lane departure alarm for alarming the driver against a departure of the host vehicle from the lane by recognizing the lane marking via a stereo camera installed at the front position of the vehicle is also making progress. In addition, the development of automobile safety devices such as a front obstacle monitoring device is progressing.
Known technology other than front monitoring, proposed in JP-A-11-321495, for example, is intended to detect an approaching vehicle from peripheral angles of the host vehicle by use of cameras installed at the rear middle, rear right quarter, and rear left quarter positions of the host vehicle. The detection is conducted by selecting the appropriate camera according to the particular position of a turn signal switch and processing an image acquired by the selected camera. The potential hazard levels of vehicle collisions are judged in accordance with an optical flow of the detected vehicle image. The image acquired by either the rear middle camera when the turn signal switch is off, the rear right quarter camera when the switch is set to the ‘right’ position, or the rear left quarter camera when the switch is set to the ‘left’ position, is processed to monitor for an approaching vehicle.